Marcher that sounds horrendous.
We handily live within an hour's drive of both sets of parents, so we avoid all overnights.
I think every time they suggest a date, suggest one about 3 weeks after. You might have to work up to it. And could you start having other commitments that reduce their visits to 3 days and gradually even less?
I think no harm would come of 'offending' them again tbh, maybe that is exactly what you need. Does your DP do his share does most of the extra work fall as wifework? If the latter, that can also change. I think you could start setting them specific jobs - could you lay the table now, could you come and chop some veg, here's a chopping board and knife. It is not necessary for you to be dictated to and made to do all the work for such regular visitors.
Could you suggest they babysit while you go out, then when they say it's too hard, suggest THEY go out for dinner so you 2 get some space?!
I am with you, I'm highly introverted and I hate having people in my space or being a visitor. But these people have a lot of other annoying behaviours that are not normal in such regular visitors - not least, that they overstay. Take back some control OP, you can do it!